The present invention relates generally to a dowel for aligning workpieces. More specifically, the present invention relates to a dowel to align two workpieces or a cabinet wall and a shelf of a cabinet in place, without an adhesive, using a friction fit.
The present invention is a dowel that is used to align two workpieces. Typically, a dowel is inserted into the openings of the two workpieces, previously glue or other adhesive or the friction fit of the dowel within the openings of the workpiece would hold the two workpieces together.
This present invention is an improved dowel with longitudinal ribs that is used to align two workpieces or a cabinet wall and a shelf of a cabinet in place, without an adhesive, using a friction fit. Previously, when adhesive was used, the workpieces could not be separated. This provides the advantage of having a knock-down capability, so that the workpieces can be disengaged or knocked down, when desired. Another advantage of the present invention is its improved latitude for tolerance variations providing a greater ability to adjust for missed tolerances, when the two workpieces are not exactly aligned. In a production line, drilling machines that make the openings to receive the dowels have a tolerance of plus or minus 0.5 mm to where the bore hole is located on the workpiece. When aligning two bores, to receive the same dowel, the error between the center lines of the bore holes can be as much as 1.0 mm, because of the errors in tolerance of the drilling machines in placement of the holes on each opposing workpiece.
In the present invention, the diameter of the bore hole in each workpiece is 0.270 inches. In the event the two workpieces are not aligned center to center, or the holes in each workpiece are not drilled in the right location, the dowel of the present invention can fit in both holes, when the centers of the holes are off as much as 0.070 inches (1.75 mm).
The adjustment the dowel can absorb is equal to twice the height of a rib of the dowel, which is 0.035 inches. This is because the ribs on both sides of the dowel are used, they represent an adjustment of twice 0.035 inches or 0.070 inches. The dowel of the present invention provides a method and apparatus to use a dowel in two workpieces, when the alignments of the bores of the two workpieces are off by as much as twice the height of the rib on the dowel. The rib height of the dowel is the distance from the base of the rib to the top of the rib.
The rib material is strong enough to carry substantial weight, but is soft enough to bend and shear. Specifically, the separation or shearing of the rib from the dowel only requires approximately ten (10) pounds of strength. The dowel is capable of supporting a load of approximately twenty (20) pounds.